135
FXUS61 KBUF 031440
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1040 AM EDT Wed Jul 3 2024

.SYNOPSIS...
After two spectacular days of weather, it will be rather sultry
today with most sites across the lake plains reaching close to 90.
Meanwhile, our stretch of rain free weather will come to an end
later this afternoon and evening when a weak cold front will
generate some showers and drenching thunderstorms. While most areas
will then be rainfree for the Fourth of July, there will only be
minimal relief from the heat and humidity.

&&

.NEAR TERM /THROUGH THURSDAY/...
Unlike the past couple of days that featured comfortable conditions,
mid summer heat and humidity will return to the region today. This
will come as south to southwesterly flow increases behind an earlier
passing warm front, causing an increasingly sultry airmass to advect
into the region. This will include Tds between 65 and 70 as evident
by upstream sfc obs over the Ohio Valley, while PWAT values will
surge to around 2 inches.

While this will initially be accompanied by plenty of sunshine, our
unstable airmass will become increasingly favorable for some showers
and thunderstorms. As is most often the case during the summer, an
approaching cold front will be preceded by a pre-frontal sfc trough
this afternoon. The latter could help to initiate some thunderstorms
over the Southern Tier during the afternoon, then more widespread
convection can be expected late in the day into the evening from the
passing cold front. The subtropical plume of moisture ahead of these
boundaries could support some torrential downpours with some of the
convection, but despite forecast bulk shear values in the vcnty of
40 kts, the risk for strong to severe thunderstorms has diminished
due to weaker anticipated lapse rates and corresponding instability.

Otherwise, temperatures today will climb to near 90 for the lake
plains of western counties while the remainder of the region should
experience highs in the mid 80s. These values will be roughly 10
degrees higher than those from Tuesday and more than 15 degrees
higher than those from Monday.

The showers and thunderstorms early tonight will diminish in coverage
after midnight....as the aforementioned cold front will slowly press
through and settle across Pennsylvania towards daybreak. Despite the
passage of the weak cold front though...it will remain warm and muggy
with the mercury only falling to around 70 for the vast majority of the
region.

For the Fourth of July...the frontal boundary and axis of sub tropical
moisture will become stalled across Pennsylvania. This should keep the
focus for showers and thunderstorms to our south...but with no real
airmass change in the wake of the front...our fair weather will
continue to include warm and uncomfortably humid conditions.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Thursday Night and Friday surface high pressure will pass by our
region to the north, with a frontal boundary stalled to our south.
Deeper moisture will be towards southern PA. Could see a shower or
thunderstorm near the State Line Thursday night heading into Friday
morning as a moist airmass lingers over our region, and a return
flow warm front lingers near our region. Also this remaining moist
airmass and light winds may produce some patches of fog, especially
across SW NYS. The light winds Thursday night will not clear
firework smoke quickly.

Chances increase midday Friday for showers and thunderstorms as the
warm front to our south begins to lift towards our region.

Greatest coverage to convection will be Friday night and Saturday,
with the passing of the warm front, low level convergence on the
nose of a 35 to 40 knot LLJ that will reside under divergent flow
aloft, and broad scale lift ahead of the shortwave. Bulk shear in
the 0-6km layer will increase to 40 to 45 knots, giving strength for
some discrete cells. Any training cluster of cells Friday night
could bring heavy rainfall with PWATs again rising towards 2.00
inches.

Overnight timing is not great for severe weather, but the kinematics
of winds aloft maintaining organized storm structure, a stronger
storm or two Friday night and early Saturday morning cannot be ruled
out. For Saturday afternoon, strongest storms will likely be across
eastern areas where lingering MUCAPE values of 1000 J/KG and 0-6 km
bulk shear values near 50 kts ahead of a cold front could boost
thunderstorms. Storms will exit east of our region Saturday evening.

Slightly cooler air Saturday night behind the front will lower
overnight lows down into the low to mid 60s.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
An area of high pressure will cross our region Sunday and Sunday
night, bringing widespread fair weather. This area of high pressure
from the mountain west, and not Canada, will not scour out the
humidity, with dewpoints still remaining near 60F within the area of
high pressure.

A few lake breeze showers and thunderstorms will be featured for
Monday with building instability through the day as surface
temperatures climb back into the mid to upper 80s. Another shortwave
trough from the Plains will near the region for Tuesday with lift
ahead of this feature likely to bring better coverage area to
showers and thunderstorms.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will be in place across our region today...but as we
work through the afternoon and first half of tonight...a pair of
boundaries will likely trigger some showers and thunderstorms. The
highest chance for this activity will come after 21z.

Cigs in the wake of a weak cold front this evening will encourage to
drop to MVFR for many areas late tonight...mainly south and east of a
line from Buffalo to Rochester.

Outlook...

Thursday...Mainly VFR with a low chance of a shower or thunderstorm
across the western Southern Tier.
Friday and Saturday... Mainly VFR with a chance of showers and
thunderstorms.
Sunday...VFR

&&

.MARINE...
A cold front will approach the region today. Winds will veer to the
southwest ahead of the cold front. While fair weather will remain in
place through at least early afternoon...there will be an increasing
risk for thunderstorms through the evening hours.

In the wake of the cold front...fair weather will return to the region
later tonight with subsiding southwest breezes.

Looking ahead to the Fourth of July...gentle to moderate winds will be
in place throughout the region. These winds will be from the southwest
on Lake Erie and primarily from the west on Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...PP/RSH
NEAR TERM...PP/RSH
SHORT TERM...Thomas
LONG TERM...Thomas
AVIATION...RSH
MARINE...RSH